Co-design of Antenna Element and Ground Plane for Printed Monopoles Embedded in Wireless Sensors

This work presents the results of a study on Euclidean and fractal small antennas operating in the 2-3 GHz range, which were designed according to the size and bandwidth constraints imposed by wireless multimedia sensor networks. The performance of small antennas depends heavily on their electrical size, which is controlled by the size of the ground plane. We cannot design small antennas for tiny sensor nodes without considering the effect of the ground plane. The tested schemes have been characterized in terms of electrical size, fractional VSWR bandwidth, and broadband total radiation efficiency. A suitable figure-of-merit is also suggested, which is an attempt to gather all fundamental antenna parameters in a single scalar quantity. The results show that a large ground plane does not necessarily produce a better printed antenna. Moreover, each antenna element couples to the ground plane in its own unique way. Meander-line antennas manage to outperform more involved antenna configurations in a fair comparison.